1. Field of the Invention
The present invention relates to cleaning processes and, more particularly, to a cleaning or surface treatment process and associated tank assembly for implementing the process.
2. Description of the Related Art
It is known that the thorough cleaning of commercial kitchen exhaust hood filters is a difficult task with the conventional equipment solutions and best practices in the market place. Commercial kitchen exhaust hood filters, or hood filters, are designed in such that the filter has areas of grease accumulation from the grease laden vapors of cooking that are not in a clear line of sight to operators of cleaning equipment. These non-line of site (NLOS) areas, or critical areas, of the filter are the primary area of shear in the air flow as the grease laden vapor passes through the filter and subsequently are the areas that accumulate the most grease deposits. For hood filters to function properly, these critical areas need to be free from grease accumulation.
As hood filters accumulate grease, two things start to happen. First, the filter becomes less efficient and allows more grease vapors to pass through. This will in turn allow for more grease deposits to accumulate on the duct work and the exhaust fan that is usually on the roof of a restaurant. As grease deposits increase in the duct work and the fan, the efficiency of the entire exhaust system is compromised, and there is an increase in fire hazard from the accumulation. Second, as grease accumulates in the critical area of a filter, the accumulated grease reduces the volume of air that can be exhausted or removed from the kitchen. This will lead to cooking vapors/smoke accumulation in the kitchen and will impact the air balance (e.g., make-up air (MUA) or heating ventilation/air conditioning (HVAC)) of the facility. Both of these situations can be avoided with clean hood filters and proper cleaning protocols set forth by the restaurant or commercial kitchen.
Cleaning hood filters is a common activity for all commercial kitchens. The conventional methods of cleaning these hood filters is either laborious or ineffective. Manually cleaning the filters by hand is not a desirable duty and takes quite a bit of time to perform thoroughly. Many commercial kitchens that have industrial dishwashers will place the filters in the dishwashers and run them through. While this process appears to clean the filter, it in fact does not thoroughly clean the filter. Due to the NLOS features of the filters, 1 and 2 degree sprays of commercial dishwashers cannot contact the critical area of the filter where the majority of the grease has accumulated. Hence, a filter will look clean to the eye, but will have hidden accumulation in the critical area and will not perform as well as a completely clean filter. Many commercial kitchens will subcontract the cleaning of filters out to service organizations. These hood cleaning companies (HCC) utilize a couple of techniques to clean filters thoroughly. For example, many HCCs use caustic soak tanks. This process involves simply placing the filter in a bath of caustic water and allowing the caustic water to completely dissolve the grease. While effective in cleaning the filter, this process takes several hours or even days to work, and most HCCs do not have the time to wait on this process. Another exemplary process involves pressure washing. Here, the HCC uses a high pressure washer to spray the filters. This process is marginally effective but is very time consuming, and requires a large area to perform the work because of high pressure spray splash. In order to clean a hood filter properly, the critical area of the filter must have all the grease removed. As previously mentioned, this critical area is not visible, hence the challenge of cleaning this area well.
It is also known that several other industrial cleaning applications, where NLOS issues persist, could be satisfied with this process and equipment solution. Some examples of this are complex castings or machined parts, which are becoming more common place with the advent of 3D scanning technology and advanced computer aided numerical controlled (NC) machining. Most complicated castings and machined parts need cleaning, and current spray booths or dunk tanks used in cleaning these parts have the same issues as hood filters. Spray booths only have 1 or 2 degree spray trajectories and dunk tanks take many hours to work properly.
It is also known that several products need surface treatments on NLOS areas, such as acid etching or anodizing. The same issues of cleaning NLOS apply to surface treatment of NLOS. Sprays cannot see the feature and dunk tanks take a long time.
Also known as is a fluids or other based process, where this forced immersion with oscillation process can be applied that acts not as a cleaning process, but a process to achieve other objectives.